Rust and oxidation inhibited lubricating compositions



Patenteci Oct. 26, 1948 RUST AND OXIDATION LUBRICATIN G COMPOSITIONS John A. Patterson and Herman D. Kluge, Beacon, N. Y., assignors to The Texas Company, New York, N. Y.', a corporation of Delaware No Drawing. Application December 8, 1943,

Serial No. 513,466

4 Claims, (on. 252-496) This invention relates to an improved lubricating composition and particularly to an oxidation inhibited hydrocarbon oil which is rendered rustproof in the presence of water by the incorporation of a novel combination of addition agents.

Hydrocarbon oils used in lubricating compositions are usually subject to deterioration caused by heat and aeration resulting from the conditions of operation of the lubricant. This deterioration or oxidation causes the formation of acidic and sludge-like bodies which attack the bearing metals and deposit carbonaceous films on the surfaces to be lubricated. These deleterious effects have been substantially reduced by the incorporation of small amounts of so-called oxidation inhibitors which retard or minimize the formation of these acidic and sludge-like bodies in the oil.

Such inhibited lubricants have given satisfactory service in the lubrication of dry systems, but an added problem is encountered in lubricating systems where small amounts of water may accumulate. It has been found that such conditions of lubrication cause rusting or corrosion of the metal surfaces which results in uneven lubrication, increased .wear and possible seizure between parts of narrow clearances due to" the sloughing-off of rust particles and entrainment thereof in the lubricant body. This is particularly 1 noticeable in the lubrication of steam-driven or marine equipment where leakage and steam condensation can hardly be avoided. To a lesser extent, rusting or corrosion is obtained in the lubri.. cation of metal surfaces exposed to humid atmospheric conditions, such as textile and other industrial equipment, or in the lubrication of en closed systems which are subject to intermittent operation, such as internal combustion engines,

railway equipment, etc., which allow condensation within the system or parts thereof during the standingperiods.

It is thepurpose of this invention to provide a lubricating composition which possesses both rust-proof and oxidationeresistant properties and also a method of inhibiting oxidation-resistant lubricantsso as to minimize the formation of rust or corrosion upon metallic surfaces lubricated- It has also been discovered that a hydrocarbon oil, such as a. mineral lubricating oil, which is compounded with an oxidation inhibitor and the combination of a dicarboxylic acid and an organic acid ester of an acid of phosphorus, possesses greater oxidation-resistant properties than are obtained with the oxidation inhibitor, per se.

The oxidation inhibitors which may be used in conjunction with the combination of the dicarboxylic acid and the organic acid ester of an acid of phosphorus are those which normally provide 7 a resistance to oxidation when compounded with a hydrocarbon oilor lubricating composition subject to operation in the presence of water. These inhibitors are usually water-insoluble and resist ant to hydrolysis or decomposition in the presence of water. Compounds o'fthis nature, which are effective anti-oxidants in the presence of water, may be generally classified into three types of compounds, amines, aromatic hydroxy compounds, and sulfur-containing compounds. The amounts in which these inhibitors are incorporated in a hydrocarbon oil or lubricating composition are usually within the range of 0.01-5.0% by weight and, in most instances, between (ll-2.0% by weight. n

It has been found that by incorporating an additive composition consisting of a combination cant is obtained which possesses both rust-inhibiting properties and enhanced anti-oxidant properties.

The sequence of incorporation is not a limitation of the present invention and .the various addition agents may be incorporated as a unit or each individual component may be incorporated separately. The practical aspects of the method of incorporation dependentirely upon the compatibility of the particular compounds selected.

The combination of the oil-miscible dicarboxylic acid and the organic acid ester of the acid of phosphorus is described and claimed in copending application serial No. 762,008 filed July 18, 1947, as a continuation of Serial No. 509,122 (now abandoned), filed November 5, 1943. The combination of an oil-miscible dicarboxylic acid and a diamino diaryl alkane in a lubricating composition, is described and claimed in our copending application Serial No. 632,106, filed November 30,

1945 as a continuation-in-part of Serial No. 519,- 812 (abandoned), flied ,January 26, 1944. The

namely N-substitutedaromatic disclosures thereof are directed to the rust-preventive properties and anti-oxidant properties of the respective additive compositions when applie to metallic surfaces exposed to water and being classified in either of two groups: (1) dicarboxyllc acids which exist in stereo-isomeric form; and (2) dicarboxylic acids which possess a fixed configuration. It has been found that the greatest rust protection is obtained from an additive composition in which the carboxylic groups of the dicarboxylic acid component are in a plane symmetrical configuration. In the case of the stereo-isomeric acids, this configuratlonis easily recognizable as the cis form of the acid. As examples of the types of acids falling within this classification are the alkylated phthalic acid, alkylated hexahydrophthalic acid, alkyl malonicacid, alkyl maleic acid, and alkyl citraconic acid.

In its preferred form the invention contemplates a dicarboxylic acid obtained by the condensation of an olefin with maleic acid anhydride followed by hydrolysis. The condensation is carried out with an olefin, or mixtures thereof, either straight or branched chain containing an average of at least six carbon atoms and preferably ten or more. These olefins may be obtained from any of the usual sources, such as vapor phase cracking of petroleum oil or wax, or the polymerization of lower molecular weight olefins. The acids produced in this manner may exist as an alkyl maleic acid, an alkenyl succinic acid, or mixtures thereof. In order to simplify the description of these condensation products and the acids produced thereby, reference will be made throughout the specification and claims to alkyl maleic acids.

The second component of the additive composition, namely, the organic acid ester of an acid of phosphorus, embraces any organic ester of a phosphorus acid which contains at least one replaceable hydrogen linked to the phosphorus through an oxygen atom, and particularly the higher molecular weight organic esters which are soluble or miscible in the hydrocarbon or lubrieating compositions. The acids of phosphorus whose organic acid esters satisfy the requirements of the present invention are the various phosphoric acids, which include the ortho, meta and pyro acids, together with the polymeric forms 60 thereof. The organic esters of these acids may be the alkyl, aralkyl, aryl, and cycloalkyl esters, or mixtures thereof, which may be present as a monoor di-ester, depending uponthe available replaceable hydrogen present in the phosphorus acid. It is particularly desirable that these esters be sufficiently aliphatic in'nature and of such molecular weight. as to render the compound either oil-soluble or oil-miscible. Examples of the type 'of compounds falling within this classi: flcation which have been found satisfactory for use in the additive composition are the following: di-lauryl acid pyro-phosphate, n-butyl oleyl ortho-phosphate, mono-lauryl ortho-phosphate, and cresyl octyl acid ortho-phosphate.

In the preferred additive compositions of this invention the previously-mentioned alkyl maleic acid' is combined with a high molecular weight alkyl acid phosphate which contains a total of at 5 least 10 carbon atoms in the ester radicals thereof. These alkyl acid phosphates may be prepared by any of the known methods of synthesis and may consist of mixed alkyl esters, such as butyl lauryl acid ortho-phosphate or mixtures 10 of monoand iii-substituted esters, such as monoand di-lauryl acid ortho-phosphate, as well as the simple esters, such as mono-lauryl acid orthophosphate.

The amounts of the individual components of the additive composition to be incorporated in the hydrocarbon oil or lubricant will vary in accordance with the degree of rust protection and oxidation-resistant properties required. As a general proposition the dicarboxylic acid may be incorporated in ranges between 0.005 and 3.0% by weight, and the organic acid ester of an acid of phosphorus in ranges between 0.0001 and 2.5%

by weight. In certain types of oils whose specifications include a maximum neutralization number, such as in turbine oil, the amounts of the acidic combination incorporated will necessarily have to be quite small. However, in other lubricating oils or compositions, where the neutralization number is not a serious factor and performance is the sole consideration, greater amounts of the additive composition may be incorporated.

As an added consideration of this invention, it has been found that foaming diificulties are encountered when the rust and oxidation-inhibited lubricating oils are used in certain circulatory or restricted lubricating systems, which are necessitated by recent developments in the design of internal combustion engines and other power plants where space is limited. This propensity toward foaming results in excessive frothing of tendencies of a rust and oxidation-inhibited lubricating oil, such as the compounded oils of the present invention, may be retarded or minimized by the incorporation of a small amount of an organic silicone, such as dimethyl silicone polymer.

These organic silicones may be obtained by hydrolysis of the di-alkyl or mixed alkyl-aryl silicon di-chlorides, prepared by a Grignard reaction using alkyl or mixtures of alkyl and aryl magnesium bromides and silicon tetra-chloride, and

the silicols thus formed dehydrated by heat treatment. The resulting products are usually a mixture of the polymeric silicones and condensed sillcols which have not been completely dehydrated. This product may be further polymer: ized by additional heat treatment, and organic silicones of varying degrees of polymerization and molecular weight may be obtained by varying the time and temperature of the heat treatment.

The organic'silicones, and particularly the di- 55 methyl silicones, are usually oil-insoluble and are incorporated in the lubricating oil by forming a kerosene solution thereof and incorporating the kerosene-silicone concentrate in thepil. To obtain foam-inhibiting properties amounts of the silicone need be incorporated in the oil and these amounts usually range between 0.00005% to 0.01% by weight of the silicones in the lubricating oil.

The results of numerous tests which are presented herein clearly illustrate the rust, oxidation very small and io-inhibitina pr pounded in accordance with the present inven= assasie resistant properties obtained by the oxidation- A ties of the oxidation-inhibite with the additive composition of the invention. is substantially greater than that obtained by the oxidation-inhibited oil. per se.

d oil, compounded It may be seen flOlh the results obtained that in each instance the oxidation-resistant properinhibited oils compounded with the additive com- Additional test results have indicated that oils position of the invention. the results obtained in inhibited with other well-known oxidation inhibthe proposed ASI'M oxidation test are presented. itors may also be improved by the addition of In this test, 300 cos. of the oil sample are introthe combination of a dicarboxylic acid and an duced to an oxidation cell in which is suspended organic acid ester or an acid of phosphorus. spiral coils of iron and copper wire, and 60 cos. Among the specific compounds whose oxidationof distilled water are added. Oxygen is introinhibiting powers may be improved are the duced through a fritted glass outlet into the following: oxidation cell atQ- the rate of 3 liters per hour. The oxidation cell is suspended in a heated oil gff gzggi ifi g g gz 31: :2

bath and the temperature in the oxidation cell Phenybalphamaphthglagne i 8 t is maintained at aconstant temperature oi 95 C. Alpha a] manna thylamm Y 0 samples of the o'ilare periodically withdrawn to Alpha' g determine the nejutralization number and the test Beta betwdmapgthylamm continued until a neutralization number of 2 is ortho hydroxy benzyl alcoiml obtained. 1

The reference oil used in this test was a solventgzggfggg l gg g figgg refined acid-treated and filtered lubricating oil mbenzyl tetra sulfide, within the visct sity range 0148 -51 Baybolt henyl disumde Universal at 100?:1. To the reference oil were Ddethyl ditmopoxalate added Varying accepted Benzyl diethyl dithiocarbamate inhibitors and h resulting madam inhibited Zinc methyl cyclohexyl thio phosphate oils were then compounded with the additive mmethylamlme sulmr reaction. roduct composition of the present invention. For the pfienyl mercapto qumone p purpose of this; test the additive composition slilmrized betamaphtho] n of the'tcombmauon of an alkyl malelcl S uliurized phenyl-alpha-napthylamine f and an 8115.571 acid phosphate The alkyl Ttramethyl diaminodiphenyl 'disulfl'de maleic acid was prepared by the condensation of mbhenyl mercaptyl dibutyl ether maleic acid anhydride and a polymer ga ol distillate, boilingfi'ange 392-450 F. The reaction r mmh instead of t particular was obtained highest! wi agitation for 20 bination of components used in the additive coinhours and maintaining the liqu d at a gentle position in the test, other dicarboxylic acids, and flux. Initial temp r t r final temperparticularly alkylated maleic acids obtained from ature 390 F. {titer the heating was complete oleflnsof higher or lower molecular-weight may the reaction produ was we t 6001 n beused in combination with othero'rganic acid fractionated under diminish pr to remove 40 esters oi an acid of phosphorus, such as isoamyl unreacte polymer n l w boiling reaction octyl' acid ortho-phosphate and dilauryi acid products. The aikyl maleic acid anhydride was pyrophbsphate, w a then heated at about 200 F. in the presence of an Th ru t or corrosion-inhibiting properties of equal volume of water until hydrolysis was com: the oils compounded with the additive composi- Plete and X S Water had evaporated The tion maybeillustratedby the results obtainedina resulting alkyl maleic acid possessed a Nutraliinpdifled AS'I'M rust 5!}. ing synthetic se zation No. of I 336. Th s c mponent, water. In this test a polished'steeispeciinen is namely, the alkyl acid phosphate was a mmersuspended in an agitated mixture of 300ccs. oi clal product conslsting'of a mixture of a monothe oil to be tested, and 30 cos. otfasynthetic and dilauryl acid ortho-phosphate which possea-water. The 'oil sea-watersample is main sessed an average Neut. No. of approximately 264 ta ed at 140 F. over an oil bath for 48 hours, and contained an average of about 9.3% at er which time the steel specimen is removed, phosphorus. allowed to drain, and washed with precipitation Oxidation test .hntl-Oxidant Per Cent Additive Conipositlon Per Cent gg fpfi f fig: ikFT etramet h y ldiamino diplienyl methane 0.2 333 Ref. Oil+Betaoz 114 Ref. 0ll+Buty1 hni'mh hflml 0, 1 Bel. Oil-i-Tetraamyl'thiuram disulilde 0.2 250 Bar. o tl ui'iy it igtttfittsza:

Alkylmaleic acid Lauryl acid phosphate.. 80 ReLOil Tetramethyldlamino diphenylmethane. 0.2+ Composition 2) 139a Bei. oil Betao2+ gcompositon 1) no & Do.. 0.2+ Composition 2) 30o Ref. Oil Butyl beta-naphthol 0. 4+ do R91. Oil Phenyl alpha-naphthylamina 0. 2+ ....-do 670 Do i Y 0.4+ 59; $2283 &ie'iiiti$liimn es:::::::::::::::::: 333i 3.??- Ref. 011 Acetone dlamyl msrcaptcl .0. 2+ 29 naphtha or hexane and the amount of corrosion or rust observed.

Gm. per liter Magnesium chloride (MgClaSI-DO) 11.0

Anhydrous calcium chloride (CaCla) 1.2 Anhydrous sodium sulphate (NaasOil 4.0 Sodium chloride (NaCl) 25.0

The reference oil and the components of the additive composition used in this test were the same as previously described for the oxidation test. The results obtained are as follows:

the. trimer and which possessed the following analysis:

Analysis Element percent Carbon 32.35 H drogen 8. S icon 30.60 Oxygen (by diilerence). 23.00

Although the oils compounded in accordance with the present invention have been shown to possess excellent oxidation and rustinhibiting properties, there remains another factor to be considered before the compounded oils can be successfully used in operation in certain types of modern power plants. This factor is a tendency of the oil to foam in restricted lubricatin systems. As previously mentioned, these rust and oxidation-inhibited oils may be further inhibited against foaming by the addition of an organic silicone, such as a dimethyl silicone polymer. The following tests have been designed to determine the tendency of lubricating oil foam, which is produced by mechanical agitation in the presence of air, to break and return to the oil phase:

200 grams of the test oil are weighed into an 800 cc. beaker and brought up to a temperature of 120 F. After-reaching the test temperature, the oil is agitated for three minutes with a doublepaddle mechanical stirrer operating at a constant speed of 980-1000 B. P. M. Thereafter, the stirrer paddles are allowed to drain for fifteen seconds and the contents of the beaker poured quickly into a 500 cc. graduated cylinder. While maintaining the oil in the graduate at 120 F., the volume of oil plus foam and clear oil is read at ten minute intervals for 60 minutes, and the volume of foam is determined as the difference between the two readings.

In this test the reference oil used was a solventrefined, acid-treated and filtered lubricating oil within the viscosity range of 418-515 S. U. at 100 F. This oil was then compounded with 0.01% alkyl maleic acid (prepared in accordance with the example given for the oxidation test); 0.0025% lauryl acid phosphate and 0.2% tetramethyl diamino diphenyl methane. The results obtained showed 225 cos. of foam at 60 minutes, with a duplicate run showing 235 cos. of foam at 60 minutes. To this test oil were then added varying amounts of an organic silicone polymer. The particular polymer used was a dimethyl silicone polymer which consisted substantially of j T A rance Anti-oxidant Percent Additive Composition Percent 55 83961 pec men Ref. Oil Heavy Rust. Ref, 011 +Tetramethyldiammo diphenyl methane 0. 1 Do. Bet. on Tetramethyldinmi o p e r et ane {fifiitig flgggfig g: g, }Clean Ref. Oil Tetramethyldiamino diphenyl methane 0. 2+ giyl y g'g g gg a 9 3 Do. Aiky maioic acid. .II 0103 an. on Beta-nap t a new o, 005 0 0 2+ Alky maleic acid 0.01 Do s kiiikuryl aclid phoislphated. (0)925 y me on: no f. Raf. Oil P enrl aiphanaphthvlamine y; 8cm phosphate M025 D0 0 4+ {Alky maleic acid 0.01 Do Lsuryl acid phosphate 0. 0025 Ref. Oil Tetra amyl thiumm disuiflde iggm fifififig g g 3: 83

7 Alkyl maleic acid 0. 0i Ref. Oil Acetone die-my ercapt "7 Lam] acid phosphate 0. 0025 1. A lubricating oil composition having superior anti-oxidant and anti-rusting properties in the presence of water comprising as essential ingredients a hydrocarbon oil possessing lubricating properties and having incorporated therein about 0.01-5.0% by weight, on the basis of the lubricating composition, of "an alkyl substituted diamino diphenylmethane, about 0.005- 3.0% by weight of an oil-miscible dicarboxylic acid having at least 10 carbon atoms in the molecule and a plane symmetrical configuration, and about 0.0001-2.5% by weight of an oil-miscible alkyl acid phosphate containing at least 10 carbon atoms in the alkyl portion thereof.

2. A lubricating oil composition having superior anti-oxidant and anti-rusting properties in the presence of water comprising as essential ingredients a mineral lubricating oil having incorporated therein about 0.1-2.0% by weight of tetramethyl diamino diphenyl methane, about 0.005-3.0% by weight of an oil miscible alkyl maleic acid having at least 10 carbon atoms in the molecule, and about 0.0001-2.5% by weight of an oil-miscible alkyl acid phosphate having at least 10 carbon atoms in the ester portion thereof.

3. A lubricating oil composition having superior anti-oxidant and anti-rusting properties in the presence of water comprising as essential ingredients a mineral lubricating oil having incorporated therein about 0.1-0.2% by weight of maleic anhydride with a polymer gasoline distillate, and having at least 10 carbon atoms in the'molecule, and about 0.00250.005% by weight or a lauryl acid orthophosphate.

4. A lubricating oil'compo'sition according to,

claim 3, wherein the mineral lubricating oil also has incorporated therein about 0.0001-0.002% by weight of an oil-insoluble alkyl silicone polymer.-

JOHN ,A. PATTERSON. HERMAN D. EUGE.

REFERENCES CITED The following references are of record in the file of. this patent:

Number 10 mm STATES m mu'rs Inrsen May 1, 1945 

